Floating roof structure



y 0, 1969 D. L. KORN 3,445,026

FLOATING ROOF STRUCTURE Filed March 22, 1968 Sheet of 2 INVENTOR DONALD L. KORN Mflok.

ATTORNEYS D. l... KORN FLOATING ROOF STRUCTURE MayZO, 1969 Sheet 2 Filed March 22, 1968 United States Patent 3,445,026 FLOATING ROOF STRUCTURE Donald L. Koru, 1225 Circle Drive, Sapulpa, Okla. 74066 Filed Mar. 22, 1968, Ser. No. 715,271 Int. Cl. B65d 87/20; F161 9/00; E0411 7/12 US. Cl. 220-26 7 Claims ABSTRACT OF THE DISCLOSURE A plastic floating roof for particular use with fixed roof type tanks includes adjustable supports for supporting the roof either at a level for cleaning the tank beneath or at another level representing the lowermost level of liquids within the tank. The roof is constructed to allow for cleaning or repair above and below the floating roof and in addition support persons thereon when the tank is empty.

Background of the invention Floating roof tanks for normally vaporous liquids are well known in the art. However, these structures are ordinarily quite elaborate and are constructed so as to leave the tank open above the roof. The purpose of a floating roof is to prevent vapor losses, as a safety measure to prevent explosions or asphyxiation of personnel, and to mitigate air pollution. However, many closed roof tank structures exist and are built where vapor loss and safety problems still exist. Further, some form of lower supports or legs attached to and beneath the floating roof must be provided if any cleaning is desired. In many instances these lower supports interfere with any necessary cleaning and repair below the floating roof.

Plastic floating roofs of the type formulated and formed in accordance with the teachings of US. Patents 2,907,627

and 3,158,667 have not considered the problems involved when the tank is empty for cleaning or repair either below or above the floating roof. More importantly, these roof structures do not support persons thereon when the tank is empty.

Summary Accordingly, this invention discloses methods of forming plastic floating roofs and apparatus for supporting such roofs in a variety of desired positions within the tank to permit repair and/or cleaning of the tank above and below the roof.

Brief description of the drawings Description of the preferred embodiments In the drawings, and in particular FIGURE 1, a tank sidewall structure 10 includes a fixed roof 12 and in some instances a base portion 14. A suitable manhole opening, not shown, is typically provided in the lower six feet of the tank for the purposes of gaining access to the tank bottom from time to time. Likewise in the upper portion of the tank such as 16 suitable manhole may be provided in the sidewall and/or in the roof with suitable means to allow personnel to enter the tank chamber at any level therein. Formed and supported within the tank is the floating roof of this invention generally designated by the numeral 18 and more specifically hereinafter described. In larger tank structures interior columns 20 are provided to add structural support to the roof 12. These columns may in some tanks include tubular and vertical gagewells for taking appropriate measurements of the liquid below the roof from positions above, usually from a structural fixed roof opening into the well. In some instances, however, these are omitted, using suflicient radial-like roof supporting structural members. In the embodiment of this invention a plurality of roof stop members 22 are attached at various places around the inner periphery of the tank sidewall 10 at a common level. Additional stop members 24 are incorporated with the interior columns 20 at the same level at those members 22. A plurality of vertically suspended flexible cable or chain members 26, more specifically described herein, are provided for vertically supporting the roof 18 in a plurality of positions from atop the lower stop members 22 and 24, to a position substantially adjacent the roof thereof if desired. At least one vent member 17 is provided in the sidewall of the tank as an upper limit of floating movement, by the outflow of liquid; otherwise the roof would be crushed against the fixed roof. Additional support cables or chains 28 are provided as shown and described more fuly hereafter.

Referring now to FIGURE 2 the floating roof 18 of this invention is depicted and enlarged. The roof structure comprises a lower foundation or pan shaped portion 30 which is formulated preferably of polyester resin and fiberglass. The foundation is so formed so as to include an upwardly and outwardly flange rim 32 to which a resilient seal flap 32 is attached to seal the space between the outer rim and the outer sidewall of the tank 10. At those places adjacent a vertical column or other vertical member within the tank, an upwardly and outwardly formed flange or rim 36 is provided which likewise includes a resilient seal flap 38 circumscribing around the interior column. Typically the rim seal flaps 34 and 38 are of a flexible material appropriate to the fluids used within the tank. For example, resilient neoprene rubber is useful in crude oil storage tanks. The inner flap 38 is of about the same diameter of rim 36 being thereafter slit or cut to conform with the shape of the interior column 20. For example, if the interior column is formed of a channel structural member a slit is made in the seal flap 38 which would correspond to the channel cross section of the structural member. Positioned at various places around the structure 18 are support rings 40 to which the vertically extending support chain 26 is fastened. Likewise additional support rings 42 are adapted to retain chain members 28. A guide roller 44 is biased normally outwardly against the sidewall 10 of the tank by a spring steel tempered member 46 which is attached at various locations, e.g., ten foot centers around the outer periphery of the roof structure.

Floatation of the roof is enhanced by the provision of polyurethane type foam material 50 which is formed thereon either alone or with inert fillers to provide additional ballast. Typically the foam is a type which is precatalyzed either within a spray gun applicator or at the spraying nozzle outlet. Typically, a thickness of from one and one-half to two inches is provided.

Referring now to FIGURE 3, in one embodiment, it can be shown that vertical chain support member 26 has incorporated therewith an eye-hook 27 at approximately three feet above the lower end. Additionally, at various places around the inner periphery of sidewall 10 of the tank are located various loops S2 to which the 3 end of chain 28 may be attached when the floating roof 18 is in a position of about six feet above the bottom of the tank.

In FIGURE 4 a manhole 60 (about 30" in diameter) may also be formed in the roof for access above and below as necessary. The opening is sealed and closed by cover 62 held to the rim 61 by bolts 64 or other fastener 'means.

In the operation and construction of this invention and after the tank shell has been thoroughly cleaned, plumbed, and made as true as possible, some preliminary welding, cutting and drilling operations may be necessary. This includes attaching the top of vertically suspended chains 26 to the fixed roof or roof supporting structure. Additionally, hook members 52 are attached around the inner periphery of the tank shell a desired level. If a manhole 16 is not already provided this is also attached at a position of about nine feet from the ground level. The chains 26 are substantially of a length whereby after formation of the roof and attachment to eye-members 40 of floating roof 18, they will assist in supporting the roof at a lowermost level of about three feet from the bottom, the primary support being members 22 and 24. By entering appropriate openings within the lower three feet of the tank a plywood platform is formed on suitable supports from the bottom at a level of about six feet from the bottom, thus, allowing suflicient clearance for men to operate thereunder. This plywood platform substantially covers the cross-sectional space of the tank and is substantially parallel to the bottom. The top of the plywood platform is coated with a silicone or other type of mold releasing agent or material. The outer and inner rims 32 and 36 formed of a polyester resin-glass material may be substantially preformed in sections outside the tank. These are positioned upon the platform in proper position. Rows of glass mat and polyester resin are then applied upon the platform, bonding the outer and inner rims 32 and 36 therewith. The steel plate and chain ring members 40 and 42 previously positioned, are incorporated into the mat and resin layers at the various positions. Thereafter a polyurethane foam, of thickness from one and one-half inches to two inches, is sprayed either alone or with some form of inert filler materials upon the polyester resin-glass foundation 30 which bonds there-with. The foam is formed by a process in which the catalyst is premixed with the foam forming material in the spray gun. As a seal for the foam, a thin protective coating 51 is added by spray, roll or brush to preclude penetration of any liquids which may accumulate atop the roof. The coating 51 is preferably a polyester resin with or without fibrous or other filler material. Thereafter the lower end of chains 26 are attached to support ring 40 in a manner typified as shown in FIGURE 3. Likewise chain 28 is attached to eye 42 and thence book 52 at the various spaced places around the inner periphery of the tank.

In another embodiment, especially when the roof is to be supported at the six foot level, slotted portions 21 are formed through member 20 within which a pin member 23 may be inserted. A similar opposite opening is provided in the inner rim portion 36 to receive the pin. This provides additional support. At various places preferably at a level of about three feet, lower stop members 22 and 24 are positioned throughout the tank. Seal flap members 34 are attached to the outer rim 32 and the inner seal flaps 38 to the inner rims 36. Thereafter the plywood platform is dismantled and removed through the lower opening. Beneath the floating roof 18 the spring tempered member 46 and guide roller 44 are attached to the foundation 30 at desired spaced intervals and at desired tension against the tank 10.

The lower openings in the tank are closed and the tank is ready for filling. Hooks 27 of the chain 26 are removed. When liquid, entering from below the roof, reaches the level of the roof it will float thereon. Chains 28 are removed from hooks 52 and pins 23 are withdrawn.

The men within the upper part of the tank will leave through the manway 16 or like opening which is thereafter enclosed and sealed. In normal operation and breathing of the tank the roof 18 of this invention rises and falls with the changing levels of the tank.

As such, this invention provides an economical and low cost floiating roof structure capable of being formed within a closed roof tank and supported at a first level, approximately six feet, to permit men to work beneath the floating roof, yet is adequately supported to allow men to work above. In addition the roof can be supported at a second level which is the lowermost level of liquids within the tank, hence preventing any vapor space to be formed in the tank.

Although the floating roof invention is described in relation to fixed roof tanks having vertical supports 20, it is to be understood that the invention is applicable to those tanks without such supports. In such event a vertical keyway-type guide is affixed t0 the tank sidewall 10 to prevent unnecessary rotation of the floating roof as it breathes with the liquid. Further, the inventive and claimed concepts of a fixed roof are applicable to a tank which has support members at the upper end of'the cylindrical shell 10 but not a closed or covered roof.

Additionally the application of the support members 26 and 28 to floating roofs of metallic type is also inclusive of this invention.

The invention has been described with reference to specific and preferred embodiments. It will be apparent, however, that other modifications can be made without departing 'from the spirit and scope of the invention.

What is claimed:

1. The combination of a fixed roof liquid storage tank structure having a floating roof therein, the improvement comprising:

means including a plurality of first flexible cable or chain members extending vertically from said closed roof or roof support structure and interiorly of the tank to a connection with said floating roof and adjustable to support said roof in the absence of liquid thereunder at a first lower position and at a second upper position;

means including hook openings circumferentially spaced and attached at the same level to said tank sidewall around the inner periphery thereof; and

means including a plurality of second flexible cable or chain members spaced from and about the outer periphery of said floating roof at the substantially same circumferential spacing as said hook opening means, and substantially radially opposed thereto said second members of length to support said floating roof at said upper position.

2. The combination of claim 1 wherein said tank includes a vertical keyway-like member to prevent rotation of said floating roof therein.

3. The combination of claim 1 wherein said tank includes:

at least one vertical support member from the base to the roof therein;

a plurality of stop members attached to the inner periphery of said tank and to said vertical support member along a common horizontal plane equivalent to the normally lowermost liquid level, said stop members adapted to permit said floating roof to rest thereon.

4. The combination of claim 1 wherein said floating roof comprises:

a lower foundation including an outer flange rim of diameter less than the inner diameter of said tank, said foundation composed of polyester resin and fiberglass filler material, a resilient seal flap attached to said rim and extending into contact with the inner periphery of said tank;

a polyurethane foam material sprayable attached to the upper portion of said floating roof; and

a protective seal coating the upper surface of said foam material.

5. The combination of claim 3 wherein said floating roof comprises:

a lower foundation including an outer flange rim of diameter less than the inner diameter of said tank and an inner rim surrounding said vertical support, said foundation composed of polyester resin and fiberglass filler material, a resilient seal flap attached means including hook openings circum'ferentially spaced means including a plurality of second flexible cable or chain members spaced from and about the outer peto each of said rims and extending into contact with the inner periphery of said tank and said support respectively;

a polyurethane foam material sprayable attached to the upper portion of said floating roof; and

a protective seal coating the upper surface of said foam material.

6. The combination of claim 1 including an overflow vent in the sidewall of said tank situated adjacent the upper end thereof to define the upper travel limit of said floating roof Without its touching said first roof or roof support structure.

7. The combination of a fixed roof liquid storage tank structure having a floating roof therein, the improvement comprising:

means including a plurality of first flexible cable or chain members extending vertically from said closed roof or roof support structure and interiorly of the tank to a connection with said floating roof and adjustable to support said roof in the absence of liquid thereunder at at least one position;

riphery of said floating roof at the substantially same circumferential spacing as said hook opening means and substantially radially opposed thereto, said sec- 0nd members of length to support said floating roof at said one position.

References Cited UNITED STATES PATENTS 1,700,887 2/1929 Glass 220-26 2,036,372 4/1936 Stough 220 -26 2,050,686 8/1936 Wiggins. 2,663,452 12/1953 Wiggins 220-26 2,873,042 2/1959 Fino 220-26 2,914,212 11/1959 Fino 22026 3,036,342 5/1962 Fino 220-26 3,240,381 3/1966 Smith -2 22026 3,372,831 3/1968 Daniels et al 22026 FOREIGN PATENTS 1,382,329 11/1964 France.

JOSEPH R. LECLAIR, Primary Examiner.

JAMES R. GARRETT, Assistant Examiner. 

